FOLEY, Minn. — It does seem out of place to be talking about scouting at this time of year. Yet, for those acres of corn still standing it may be appropriate to do just that. Tar spot is a fungal disease in corn that has been known to cause significant yield loss in areas to the south of Central Minnesota. This disease is relatively new to both the US and to Minnesota. At this point until the end of harvest is a good time to scout for this important disease.
Symptoms include irregular shape black structures on leaf surfaces. The black structures are firm, appear mostly smooth on the surface and the spots do not rub off or break open. Tar spot can also produce fisheye symptom that have black spots surrounded by tan lesions with dark borders.
The above information is from the “Tar spot of corn in Minnesota: 2021 Edition” post in the Minnesota Crop News blog. If you suspect you have a field with tar spot contact either me at email@example.com, or call at 608-515-4414 or Dean Malvick at firstname.lastname@example.org. To receive future events, educational programming, and agronomic updates by email, signup at z.umn.edu/tricountysignup.
— Nathan Drewitz, University of Minnesota Extension